A fluorescence measuring device comprising an illuminator is known from DE 41 15 401 C2. The illuminator of the fluorescence measuring device comprises two illuminating units each comprising a light source, of which at least one unit is pulsed, and a diffraction grating, which is illuminated by the two illuminating units in such a way in its entrance slit plane that the two beam paths originating from the illuminating units are combined in its exit slit plane and emerge therefrom in one beam path, forming a bichromatic intensity-time profile of varying wavelength. The known fluorescence measuring device serves, according to the details in the patent specification, to determine the ion concentration of an object under investigation, which has been coloured with a fluorescent dye, whose excitation maximum varies as a function of the ion concentration to be determined. By means of an imaging system, the beam path with the bichromatic intensity-time profile is directed on the object under investigation. A detector unit is provided for converting the fluorescent light output by the object under investigation into a measurement signal. The two illuminating units are distinguished in that they each comprise a light guide, whose entrance aperture is exposed via an imaging system to light from the light source assigned thereto and whose exit aperture lies in the entrance slit plane of the diffraction grating. The exit apertures of the light guides are displaceable relative to one another and to the diffraction grating for adjustment of the wavelengths of the light with the bichromatic intensity-time profile impinging on the object under investigation. As far as the structure of the illuminating units is concerned, it is proposed that these comprise two flash lamps as light sources. It is also proposed that the two pulsed illuminating units each comprise a continuous light source and an controllable shutter arranged in the beam path between said light source and the diffraction grating. It is further proposed that the two pulsed illuminating units comprise a common, continuous light source and two separately controllable shutters arranged in the beam path between said light source and the diffraction grating.
A further fluorescence measuring device is known from DE 42 28 366 C2 for determining ion concentrations of an object under investigation dyed with fluorescent dye altering the absorption or fluorescence characteristics as a function of the ion concentration. The fluorescence measuring device comprises an illuminator, a detector unit for receiving the fluorescent light and an evaluator. The illuminator comprises a polychromatic light source and means for selecting predeterminable wavelengths at short time intervals for fluorescent excitation or for simultaneous fluorescent excitation of the object under investigation with any desired predeterminable exposure time for each wavelength and any desired predeterminable dark periods. As means of selecting the predeterminable wavelengths, a holographic volume grating is provided, which is arranged on an adjustable scanner, which may be adjusted into the appropriate wavelength position for generating the wavelengths and setting the exposure time and into a wavelength position which does not excite the system for setting the dark periods. It is proposed to operate the volume grating as a reflection grating.
Further known devices, which may in principle be used as illuminator or as part of an illuminator, are known from U.S. Pat. No. 5,285,254, which describes a monochromator, U.S. Pat. No. 3,907,430, which describes an optical bandpass filter, and U.S. Pat. No. 4,575,243, which describes a monochromator. Reference is further made to U.S. Pat. No. 4,660,975.